Mount Prospect, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

017
FXUS63 KLOT 221915
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
215 PM CDT Sun Mar 22 2026

.KEY MESSAGES...

- Slight chance for rain this evening as temperatures continue
  to drop overnight

- Cooler weather to start the week before temperatures moderate
  by midweek

- A chance for showers and storms on Thursday

&&

.DISCUSSION...
Issued at 215 PM CDT Sun Mar 22 2026

Conditions remain blustery across the area this afternoon in the
wake of this morning`s cold frontal passage. Winds remain out of
the northeast with gusts 30 to 35 mph, with occasional gusts in
excess of 40 mph. These winds will continue through the
afternoon, not diminishing until this evening. Additionally, in
this post-frontal world, a slug of mid level moisture continues
to pass over the area trailing the front as it moves to the
southeast. This has resulted in a number of returns developing
on radar. Cannot completely rule out a sprinkle or an occasional
light shower to develop, but forcing is weak and low level dry
air may just keep it confined to virga. One interesting thing
of note, if (and it is a big if) it were to precipitate, some
light sleet cannot be completely ruled out. Temperatures across
the area have been steadily falling through the day and are
already in the upper 30s in northern Illinois. With colder air
aloft moving in with the moisture, there are some model
soundings that support the possibility of sleet. However, the
lack of confidence in ice presence in the cloud layer prevented
it from being added to the official forecast presently. If
temperatures were to fall quicker than expected as the moisture
moves through, a targeted update to the forecast may be needed.

A broad surface ridge will grow and slide over the northern
region tomorrow. Winds will become light and temperatures will
remain cooler with high temperatures only reaching into the 40s.
As a dry air mass overspreads the area, no precipitation is
expected through Wednesday morning. Surface winds will return to
the south-southwest on Tuesday helping to advect slightly
warmer air into the region through mid week. Temperatures should
gradually moderate into the middle of the week, returning to
50s and maybe even 60s by Wednesday.

Despite the surface winds turning to the south, a broad upper
level ridge over the southwest will keep northwest steering flow
over the region. Models continue to suggest a weak impulse will
pass over the region on Wednesday, which keeps the NBM
suggesting the slight (less than 24 percent) chance for rain
Wednesday evening. However, QPF looks meager at best. There was
no need to remove it from the forecast, but confidence remains
low.

The next deeper trough looks to descend down from the Plains on
Thursday morning. As it does, surface low is projected to
develop over the mid-Mississippi Valley in the afternoon and
move eastward over Central Illinois. With p-wats well over an
inch available, this looks like the next best chance for rain
over the area. With warmer temps and some instability in the
warm sector, there is a chance for thunderstorms as well. There
is plenty of uncertainty in temperatures during the afternoon.
The NBM came in warm with high temps well into the 70s and even
some low 80s around and south of US-24. However, ensemble mean
high temperatures have the area mostly in the mid to upper 60s
with some 70s south of I-88. Additionally, how quick an
associated surface cold front moves over the area will need to
be monitored. With plenty of instability present, a slower
progression would increase the chances that thunderstorms could
become strong to even severe. Behind that cold front though is a
much colder air mass, so while slower progression helps a
severe risk, a quicker movement increase chances that snow could
briefly mix in with any rain as it departs the area. While
there is a nice picture available in models for Thursday, a lack
of agreement in models lowers confidence in timing, coverage,
impacts, etc.

An upper level ridge out west will grow and slowly expand
eastward late in the week, projecting drier and moderating
temperatures into next weekend.

DK

&&

.AVIATION /18Z TAFS THROUGH 00Z TUESDAY/...
Issued at 1238 PM CDT Sun Mar 22 2026

Key Messages:

- Gusty north-northeast winds of 25-35 kt continue into early
  this evening before gradually abating.

- Low MVFR CIGs also expected to persist/move into area
  terminals through much of tonight.

North-northeast winds have been a bit stronger than previously
anticipated, particularly at ORD and MDW, where some
occasional gusts have exceeded 35 kt. While such gusts will
continue to be possible this afternoon, thinking is that the
more frequent gusts will be in the 30 to 35 kt range for the
main Chicago area terminals, and more in the 25 to 30 kt range
at KRFD and KDPA. The gustiness will gradually abate this
evening. Lighter northerly winds will persist into Monday, then
shift back to the northeast with a lake breeze Monday afternoon.

A rather expansive deck of MVFR stratus also continues to shift
southward into northern IL and northwestern IN early this
afternoon. Expect these CIGs to be the lowest (1,000-1,500 ft
AGL) closer to the lake through the day, with most areas not
scattering out until sometime later tonight or early Monday
morning. Thereafter, VFR conditions should return for much of
the day Monday.

KJB

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...Gale Warning until 10 PM CDT this evening for the IL and IN
     nearshore waters.

&&

$$

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